how can we have relatively simpler touch gestures? mostly what I'm thinking about is long press for imitating a right click, but text selection with popup copy/paste/etc buttons would also be useful.

I would say it's also inconvenient that we don't have a good touch keyboard for wayland, but you probably know that.
maliit is hard to build, afaik not packaged for any distro, buggy and not customizable (or if it is, it is not documented anywhere else than the code), apparently there is no way to limit it's width, which makes usage harder on tablet sized screens. it has also been abandoned by the devs.
squeekboard is not compatible with KDE wayland because of missing protocols.
onboard is X only.